The U’s have endured a miserable festive period so far, picking up one point from a possible nine to slip down to fifth place in Sky Bet League Two.
For the first time this season they have lost successive league games and the latter, a 2-0 defeat to Scunthorpe United on Sunday, was described by Wilder as the poorest display of the campaign.
The U’s squad has attracted lots of praise for their battling qualities in recent months and their manager is demanding a vast improvement.
Wilder said: “Are we up for the fight when the pressure is on for the second part of the season?
“This is possibly the first time this season we’ve had a blip, losing consecutive games.
“Now we have to show what we’re really like, whether it’s the younger players or the senior ones.
“Everyone has talked about the plaudits for the senior players and defensively how good we are.
“Well, let’s have a little look now.”
United will take comfort from the fact they head to Wales with the best away league record in the top six tiers of English football.
But Rodney Parade has provided the backbone to Newport’s challenge in the leading pack, picking up 22 points there from a possible 27.
In the wake of the defeat to Scunthorpe, Wilder is considering shaking up the side.
The U’s boss does not have a great deal of scope for rotation, especially with Dave Kitson still suspended, but revealed one player would certainly be promoted from the bench.
He said: “Definitely, Michael Raynes will come into the team.”
Newport have problems of their own, with manager Justin Edinburgh facing a headache in goal.
First-choice keeper Lenny Pidgeley fractured a thumb in Sunday’s 1-0 defeat at Burton Albion and his deputy, Jamie Stephens, is out with a hamstring injury.
It could see County’s under 18 goalkeeper Connor Christie thrust into the limelight, but Pidgeley may be able to play through the pain.
Newport Co: from Pidgeley, Pipe, Oshilaja, Yakubu, Sandell, Jackson, Flynn, Chapman, Willmott, Washington, Jolley, James, Naylor, Minshull, Burge, Crow, Barker, Worley, Christie.
Oxford Utd: from Clarke, Hunt, Mullins, Wright, Newey, Williams, Hall, Rose, Rigg, Smalley, Constable, Raynes, Davies, Marsh, O’Dowda, Ruffels, Long, Crocombe.